The present invention relates to high-strength touch panels disposed on screens of LCDs (liquid crystal displays), CRTs (cathode ray tubes), etc. which provide for positional input when pressed from above by a finger, a pen, or the like in accordance with instructions seen through the screen, and a method for producing the same.
There has conventionally been used a touch panel of a resistance film type, which comprises an upper electrode sheet having electrodes and a hard coat layer at opposite faces of a flexible transparent film, and a lower electrode sheet having electrodes at one face of a glass substrate and opposed to the upper electrode sheet via spacers, with peripheral edge parts bonded by an adhesive sheet. In a method of manufacturing the touch panel, generally, the upper electrode sheet and lower electrode sheet, both of a large size to provide for many electrodes, are formed and bonded to each other, and then notches are formed from the side of the upper electrode sheet with the use of a cutter such as a metallic blade, whereby the upper electrode sheet is cut for separation of the electrodes. At the same time, the bonded body is notched with the use of a cutter from the side of the lower electrode sheet, whereby grooves are formed in the glass substrate of the lower electrode sheet for separation of the electrodes. When the lower electrode sheet is separated along the grooves of the glass substrate, the bonded body is divided to obtain individual touch panels.
Typically these days, the touch panel becomes loaded on displays of portable information terminals. Although this raises a question of the strength of glass of the touch panel when subjected to impact, for instance, when the touch panel is dropped, the touch panel manufactured in the conventional method is lacks sufficient strength.
The hard coat layer at the uppermost part of the upper electrode sheet in the prior art is intended to improve the sliding property at an input face of the touch panel and prevent flaws, but is nevertheless flaked off from both sides of cutting lines of the upper electrode sheet when the upper electrode sheet is cut with a cutter such as a metallic blade.
Further, in the conventional technique, cutting is formed with the use of the cutter from both faces, i.e., the upper electrode sheet and lower electrode sheet. In other words, alignment between the cutting lines of the upper electrode sheet and the grooves formed in the glass substrate of the lower electrode sheet is an important factor. However, the alignment therebetween is difficult to achieve because the cutting lines as well as the grooves are formed by the cutter such as the metallic blade or the like in a breadth of smaller than 0.1 mm.
For solving this issue of alignment, instead of notching from the lower electrode sheet, notches might be formed only from the upper electrode sheet by the cutter, thereby cutting the upper electrode sheet and at the same time grooving the glass substrate of the lower electrode sheet. In comparing this method with the technique whereby the grooves are formed in a separate process in the glass substrate, the glass substrate is hard to cut sharp, and it is highly probable that microcracks will occur at the grooves. The glass substrate will be broken from an end face in a glass strength test and deteriorated greatly in strength. The method is therefore not practical.
The present invention has for its object to solve the issue and provide a touch panel including glass of superior strength and a hard coat layer of superior adhesion and a method for producing the same which facilitates or eliminates alignment in a production process between cutting lines of an upper electrode sheet and grooves of a glass substrate of a lower electrode sheet.
In accomplishing this object of the present invention, the present invention is constructed as follows.
According to a first aspect of the present invention, there is provided a resistance film type touch panel in which an upper electrode sheet having upper electrodes at one face of a flexible transparent film and a hard coat layer at the other face of the film, and a lower electrode sheet having lower electrodes confronting the upper electrodes at one face of a glass substrate are disposed to face each other over a distance maintained by spacers between each upper electrode and each lower electrode confronting the upper electrode and bonded at respective peripheries by an adhesive layer, wherein the transparent film and the hard coat layer are fused at side end parts thereby forming fused parts, so that a surface layer part of each side end face of the glass substrate adjacent to the fused part becomes a compressive stress layer.
According to a second aspect of the present invention, there is provided a method for producing resistance film type high strength touch panels, in which an upper electrode sheet having a plurality of upper electrodes at one face of a flexible transparent film and a hard coat layer at the other face of the film, and a lower electrode sheet having a plurality of lower electrodes confronting the plurality of upper electrodes at one face of a glass substrate are disposed to face each other over a distance maintained by spacers between each upper electrode and each lower electrode confronting the upper electrode and bonded at respective peripheries by an adhesive layer, and the combination is then divided into individual touch panels. The method comprises:
bonding the upper electrode sheet having the plurality of upper electrodes and the lower electrode sheet having the plurality of lower electrodes by means of the adhesive layer;
thereafter projecting a laser light beam from a side of the upper electrode sheet thereby cutting the upper electrode sheet for each of the upper electrodes, while notching from a side of the lower electrode sheet with use of a cutter thereby forming first grooves in the glass substrate of the lower electrode sheet for each of the lower electrodes; and
thereafter dividing the glass substrate along the first grooves of the glass substrate to obtain individual touch panels.
According to a third aspect of the present invention, there is provided the method for producing resistance film type high-strength touch panels according to the second aspect, the method including:
forming second grooves in the glass substrate of the lower electrode sheet under the upper electrode sheet for every lower electrode concurrently by the projection of the laser light beam when the upper electrode sheet is cut for each upper electrode by the projection of the laser light beam from the side of the upper electrode sheet; and
dividing the glass substrate along the first and second grooves at both faces of the glass plate when the glass plate is divided along the first grooves, thereby obtaining individual touch panels.
According to a fourth aspect of the present invention, there is provided a method for producing resistance film type high-strength touch panels, in which an upper electrode sheet having a plurality of upper electrodes at one face of a flexible transparent film and a hard coat layer at the other face of the film, and a lower electrode sheet having a plurality of lower electrodes confronting the plurality of upper electrodes at one face of a glass substrate are disposed to face each other over a distance maintained by spacers between each upper electrode and each lower electrode confronting the upper electrode and bonded at respective peripheries by an adhesive layer, and the combination which is then divided into individual touch panels. The method includes:
bonding the upper electrode sheet having the plurality of upper electrodes and the lower electrode sheet having the plurality of lower electrodes by means of the adhesive layer;
thereafter projecting a laser light beam from a side of the upper electrode sheet thereby cutting the upper electrode sheet for each upper electrode and forming grooves for each lower electrode in the glass substrate of the lower electrode sheet under the upper electrode sheet; and
thereafter dividing the glass substrate along the grooves for each electrode to obtain individual touch panels.
According to a fifth aspect of the present invention, there is provided a method for producing resistance film type high strength touch panels in which an upper electrode sheet having a plurality of upper electrodes at one face of a flexible transparent film and a hard coat layer at the other face of the film, and a lower electrode sheet having a plurality of lower electrodes confronting the plurality of upper electrodes at- one face of a glass substrate are disposed to face each other over a distance maintained by spacers between each upper electrode and each lower electrode confronting the upper electrode and bonded at respective peripheries by an adhesive layer, and the combination is then divided into individual touch panels. The method includes:
bonding the upper electrode sheet having the plurality of upper electrodes and the lower electrode sheet having the plurality of lower electrodes by means of the adhesive layer; and
thereafter projecting a laser light beam from a side of the upper electrode sheet thereby cutting the upper electrode sheet for each of the upper electrodes and cutting the lower electrode sheet under the upper electrode sheet for each of the lower electrodes, thereby obtaining individual touch panels.
According to a sixth aspect of the present invention, there is provided a method for producing resistance film type high-strength touch panels according to any one of the second through fifth aspects, wherein the transparent film and the hard coat layer are fused at side end parts thereby forming fused parts at the projection of the laser light beam, so that a surface layer part of each side end face of the glass substrate adjacent to the fused part becomes a compressive stress layer.